Compact semi-hermetic compressor for refrigeration circuits

ABSTRACT

A compact reciprocating compressor, specially suitable for refrigeration circuits, wherein the low-pressure cock, the high-pressure cock, and at least one porthole for oil level monitoring purposes are placed on one and the same side.

TECHNICAL FIELD

The present invention belongs to the sector of reciprocating compressors, wherein a fluid is compressed thanks to the action exerted by one or several pistons which travel inside a respective cylinder, under the action exerted by one motor which transmits motion to connecting rods via a crankshaft.

Specifically, the invention belongs to the sector of reciprocating compressors used in refrigeration circuits for compressing a gaseous heat carrier fluid, thus increasing the pressure of the latter so that it can subsequently expand in a heat exchanger and subtract heat from another fluid. More specifically, the invention belongs to the sector of semi-hermetic reciprocating compressors, i.e. those compressors wherein the electric motor that drives the pistons is enclosed inside one and the same casing that accommodates the cylinders.

PRESENT STATUS OF THE ART

In the present status of the art, reciprocating compressors comprise a casing which develops according to a horizontal longitudinal axis and accommodates internally thereto an electric motor which drives into rotation a crankshaft, by means of which one or several pistons are operated, the latter being slidingly coupled with inside respective cylinders defined inside the casing. The shape of the casing has roughly the appearance of a horizontal axis cylindrical surface.

Motion is transferred from the crankshaft to the pistons by way of connecting rods.

A head is associated with the upper portion of the cylinders and accommodates valves internally thereto and hermetically interfaces to a corresponding opening defined on the top of the casing; the oil used to lubricate the kinematic mechanisms collects in the lower part of the casing.

The head is hollow and is generally subdivided into two portions by a longitudinal partition septum, which lays in a vertical plane and defines a low-pressure suction chamber and a high-pressure delivery chamber internally to the head.

High pressures are reached inside the compressors, which is one of the reasons why high attention is paid to seal in their manufacturing; generally one or several end covers are associated with the casing and cooperate with the head to hermetically close it.

Many of the compressors used in the refrigeration industry are of a so-called “hermetic” type, a term used to identify compressors for which no disassembling capability exists; other compressors are of a “semi-hermetic” type, i.e. compressors featuring a partial disassembling capability, aiming at extracting the electric motor only upon removal of an end cover.

The sucked fluid enters the compressor via an external low-pressure cock placed on the outer wall of the casing; a suction duct is defined downstream of this cock, internally to the casing, and transfers the fluid up to the suction chamber in the head.

The fluid being sucked, which is in low-pressure and low-temperature conditions, by flowing through cools the complete compressor down, and in particular the electric motor.

The compressed fluid, which is at the highest temperature and tends to heat the whole compressor, is delivered to the external world via an outer high-pressure cock; in this regard, different constructional solutions are known.

In a first solution, the high-pressure cock is installed directly on the head, at the high-pressure chamber; this solution is particularly advantageous in terms of thermal balances, in that it rapidly moves the hot compressed fluid away from the compressor.

Conversely, in a second solution, the high-pressure cock is installed on an outer lateral wall of the casing. In a first constructional solution, the compressed fluid flows from the delivery chamber in the head up to the high-pressure cock via a delivery duct defined in the casing and leaves the latter in a horizontal direction; in this solution, the sealing face of the high-pressure cock is vertical.

According to a different embodiment, the high-pressure cock might be installed, its sealing face being horizontal; in this case, the terminal portion of the delivery duct, at the outer wall of the casing, rotates upwards and defines a small chamber which features a horizontal upper interfacing face, which the sealing face of the high-pressure cock is associated with.

A disadvantage of the second solution, as compared to the former solution, is in that it increases the amount of hot compressed fluid that remains inside the compressor, whereas an advantage thereof is in that the delivery duct offers a volume internally to which any pressure surges inherent to the reciprocating operation of the compressor at least partially homogenize.

In most semi-hermetic compressors of the present status of the art, the suction cock is placed at the compressor axis; in another, less frequent solution, the high-pressure and low-pressure cocks are installed on two opposed sides of the compressor, and specifically on that side of the head where the delivery chamber is defined and on the side where the suction chamber is defined, respectively. The latter solution has a number of advantages fluid-dynamically wise but, in this approach, the compressor shall be installed in such a way as to have it accessible on both sides, a circumstance that obliges system manufacturers to leave an appropriate clearance around the compressor.

OBJECTS AND SUMMARY OF THE INVENTION

A need is felt in the refrigeration plant industry for having less and less bulky devices available; for this reason, an object of the present invention is to provide a compact compressor that requires accessibility on one side only and consequently can be positioned, the other side being adjacent to a wall or to any other element that prevents its accessibility.

Another object of the present invention is to provide a compressor that makes installation and interconnection operations easier and faster, thanks to the fact that the operator, to perform said operations, does not need to move around the device any longer.

A last but not least object of the present invention is to provide a compressor that, performances being equal, requires smaller packings as compared to traditional compressors.

These objects and others, which will be apparent to those skilled in the art upon reading the following text, are achieved by a compressor wherein the low-pressure cock, the high-pressure cock, and at least one transparent porthole for monitoring lubricating oil level are all placed on one and the same side.

In the present patent text, when speaking about high- and low-pressure cocks and at least one porthole being all placed on one and the same side, we mean that such elements are all placed in the same portion of the lateral surface of the compressor, identified by a vertical longitudinal median plane going through the horizontal longitudinal axis according to which the compressor itself develops.

That portion of the lateral surface which receives the cocks and the porthole is in turn subdivided into an upper part and a lower part, which are above or below, respectively, a horizontal longitudinal plane going through the horizontal longitudinal axis according to which the compressor itself develops.

In one preferred embodiment, the high- and low-pressure cocks are arranged in the upper part of the lateral surface portion, whereas the porthole is defined in the lower part.

In one particularly comfortable embodiment, the compact compressor according to the present invention comprises two transparent portholes for monitoring oil level, one per side, preferably both in the lower part of the compressor.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a longitudinal cross section of a two-cylinder compressor, made according to a vertical longitudinal plane going through the horizontal axis (X) about which both an electric motor (2) and a crankshaft (3) rotate; the ends of a casing (1) are closed by two respective covers (12, 13); a head (9) is visible on the top of the casing (1), internally to which pistons (4) are shown, which travel in cylinders (5) thanks to the actions transmitted by connecting rods (10).

FIG. 2 and FIG. 3 show a side view and a top view respectively of a compressor implemented according to the present invention, in a configuration wherein a high-pressure cock (7) is directly connected to the outer longitudinal wall of the head (9), at the delivery chamber. The figures also show a low-pressure cock (6) below which there is the initial portion (11) of a suction duct defined inside the casing (1); the ends of the latter are closed by covers (12 and 13). The figures also show a transparent porthole for visually monitoring lubricating oil level.

FIG. 4 and FIG. 5 show a side view and a top view respectively of a compressor implemented according to the present invention, in a configuration wherein the high-pressure cock (7) is directly connected to a lateral wall of said casing (1) via a vertical sealing face realized at the end of the delivery duct defined inside the casing (1).

FIG. 6 and FIG. 7 show a side view and a top view respectively of a compressor implemented according to the present invention, in a configuration wherein the end portion of the delivery duct defines a small chamber which includes a horizontal upper interfacing face, which the sealing face of the high-pressure cock (7) is associated with.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The compact reciprocating compressor according to the present patent application is enclosed inside a casing (1), featuring a roughly cylindrical shape, which develops according to a longitudinal axis (X) and whose ends are hermetically closed by two covers (12, 13); an electric motor (2) is also accommodated inside the casing (1) and drives a crankshaft (3), by means of which motion is transmitted to pistons (4) travelling inside cylinders (5).

An opening is defined at the upper end of the cylinders (5), on the top portion of the casing (1), which is hermetically closed by a hollow head (9), the latter being internally subdivided by a vertical longitudinal septum which defines a suction chamber and a delivery chamber therein.

In the simplest and most functional embodiment, the compressed fluid collects in the delivery chamber and, from here, it is put in communication with the external world via a high-pressure cock (7) which is located on the outer longitudinal wall of the head (9).

The input fluid, which is in a low-pressure condition, enters the compressor via a low-pressure cock (6) located on an outer lateral wall of the casing (1), on the same side of the compressor where a high-pressure cock (7) is located, and, from the low-pressure cock (6), it reaches a suction chamber via a suction duct defined in the same casing (1); while passing through this duct, the low-temperature input fluid laps the inside of the compressor, thus cooling it down.

According to a different embodiment of the invention, the high-pressure cock (7) is located on the casing (1) and the compressed fluid reaches it starting from the delivery chamber in the head and flowing through a delivery duct defined in the inside of the casing (1).

The latter embodiment can in turn be implemented in two different configurations. The former configuration is that illustrated in FIGS. 4 and 5, wherein the high-pressure cock (7) is directly connected to a lateral wall of the casing (1) via a vertical sealing face; in the second configuration, the end portion of the delivery duct defines a small chamber which includes a horizontal upper interfacing face, which the sealing face of said high-pressure cock (7) is associated with.

In all the different embodiments, the low-pressure cock (6) is on the same side of the compressor on which the high-pressure cock (7) is located.

The transparent porthole (8) used for visually monitoring lubricating oil level is also on the same side of the compressor where the low-pressure and high-pressure cocks are located.

In a particularly complete embodiment of the present invention, there are two portholes for monitoring oil level, one at each side of the compressor. 

1. A reciprocating compressor, comprising a casing, which develops along a horizontal longitudinal axis (X) and is made accessible via at least one cover, internally to which there is coaxially accommodated an electric motor which drives into rotation a crankshaft which drives one or several pistons slidingly coupled with inside respective cylinders, via their respective connecting rods, said cylinders being defined in said casing and being closed above by a hollow head which hermetically faces onto a corresponding opening defined above on the body of said casing; a suction chamber and a delivery chamber being defined inside said head, the outer longitudinal side of the delivery chamber being put in communication with the external world via a high-pressure cock; the following elements being defined inside said casing: a low-pressure fluid suction duct, which connects said suction chamber with the external world via a low-pressure cock placed on the outer lateral surface of said casing; a lubricating oil collection area, in correspondence with which, and specifically on the outer lateral surface of said casing, at least one transparent porthole is present to monitor the oil level, wherein said low-pressure cock, said high-pressure cock, and said at least one transparent porthole are all placed on the same side of said compressor, namely on the same portion of the lateral surface of the latter, identified by a vertical longitudinal median plane going through said horizontal longitudinal axis (X), so that said compressor can be installed, the other side being adjacent to a wall.
 2. The compressor according to claim 1 wherein said high-pressure cock is directly connected to a lateral wall of said head.
 3. The compressor according to claim 1 wherein a delivery duct is defined inside said casing and connects said delivery chamber of said head to said high-pressure cock.
 4. The compressor according to claim 3 wherein said high-pressure cock is directly connected to a lateral wall of said casing via a vertical sealing face.
 5. The compressor according to claim 3 wherein an end portion of said delivery duct defines a small chamber which presents a horizontal upper interfacing face, which the sealing face of said high-pressure cock is associated with.
 6. The compressor according to claim 1 wherein said low-pressure cock and said high-pressure cock are placed above a horizontal longitudinal plane going through said horizontal longitudinal axis (X), whereas said at least one transparent porthole is placed below said horizontal longitudinal plane.
 7. The compressor according to claim 1 wherein it comprises a transparent porthole on each side.
 8. The compressor according to claim 1 wherein it is a semi-hermetic compressor.
 9. The compressor according to claim 8 wherein said casing is hermetically closed by two end covers.
 10. The compressor according to claim 2 wherein it is a semi-hermetic compressor.
 11. The compressor according to claim 3 wherein it is a semi-hermetic compressor.
 12. The compressor according to claim 4 wherein it is a semi-hermetic compressor.
 13. The compressor according to claim 5 wherein it is a semi-hermetic compressor.
 14. The compressor according to claim 6 wherein it is a semi-hermetic compressor. 